1. Field of Invention
The present invention relates generally to semi-rigid tube-bending tools and more particularly to a tool for bending semi-rigid coaxial cables.
2. Background of the Invention
The increased use of higher frequencies in microwave equipment, coupled with denser packaging, have led to a greater utilization of solid-jacketed R.F. cables referred to as semi-rigid. For example, 97 unique semi-rigid cable assemblies are used in the AN/APS-116 Radar and its associated Ground Support Equipment. Fabrication of such semi-rigid cable assemblies must be carefully performed and each assembly must, in general, be treated as a microwave component assembly due to the increased assembly sensitivity to flaws and irregularities at the higher frequency levels of the microwave band. In order to prevent such flaws and irregularities, specialized tools and techniques are required to properly fabricate the semi-rigid cable assembly.
A major step in the fabrication of a particular semi-rigid cable assembly is the forming or bending of the raw stock (which is normally straight) into the desired shaped of configuration. This is necessary to assure proper installation into the applicable equipment. Semi-rigid cable has an outer jacket (conductor) and a center conductor, separated by a Teflon-type dielectric. In exacting applications, the distance between the inner and outer conductors must remain the same, and deformation of the outer jacket (conductor) is not permitted. During the forming or bending operation, the cable must be supported and the bend made preferably in a single motion to prevent wrinkles and deformation of the outer jacket. After the bend has been completed, it is not advisable to rebend the cable.
The required bending operation has in the past been performed with the T-1107 and T-2101 bending tools manufactured by Omni Spectra, Incorporated. But, these tools are limited to use with two cable diameters (i.e., 0.141 and 0.085 inches). The tools provide for only two bend radii for each cable diameter. No means are provided for determining the number of degress of bend. The use of these tools requires extensive operator training and results in trial-and-error fabrication methods. These tools will not perform all of the required bending operations.
Other devices have been developed for specialized bending applications. In some instances common tubular stock has been used for bending mandrels. But, the use of these various tools results in specialized techniques, operator training, and the absence of standardized fabrication procedures.